This invention relates to apparatus which generates signals representing the force and direction of motion of the tip of a writing instrument.
The analysis of handwriting, as in verifying signatures, can be accomplished by sensing the forces applied by the pen or pencil used to write the signature. The sensors can be located in either the writing instrument or in the table-like structure that supports the paper on which the signature is written. For example, a patent application for "Strain Gauge Transducer System" by Crane et al., Ser. No. 451,846 filed Mar. 15, 1975, and assigned to the assignee of the present application, describes the use of strain gauges contained in a small writing instrument to sense the force applied by the pen and the directions of motion of the pen, as a signature is written. As another example, U.S. Pat. No. 3,563,097 shows a device for sensing downward force of a writing instrument on a tablet of a table-like apparatus. In many situations, a table-like structure is desirable, because it avoids the need for wires to extend to the writing instrument. However, previous table-like apparatus has been relatively bulky, and also has sensed only simple downward force of the writing instrument.